I would like to create a PERL script

Well, that'll be hard because first you'll have to write this PERL language which lots of people talk about despite it not actually existing. Maybe you should use the fantastic language Perl which lets you do this easily.

As for your question, try to put the following lines together in the right order (I'm not trying to be an ass, but your question feels like homework and you should at least have to work a little bit ;-)

}
or die "horribly";
('a'..'z')
mkdir $_
{
for
[download]

Update: well, I'm sorry I helped now that you've changed your node to insult people who have tried to help you and made clear that you're not here to learn but have your work done for you. Won't happen again.